As photography develops there is an increasing availability of photographic laboratories which develop and print films originating from photographic shops. In practice the amateur or professional photographer hands the exposed films to the shop for developing and printing, and the shop transmits them to the photographic laboratory after inserting them into envelopes known as "processing envelopes".
Here, after extraction from the processing envelopes, they are developed and printed, and after treatment the negatives and prints are reinserted into the processing envelope to be returned to the shop, which then consigns them to the customer.
The complete operational cycle undergone in the photographic laboratory, i.e. the cycle commencing with the reception of the processing envelopes and terminating with the re-delivery of the processing envelopes, has as its final stage the sorting of these envelopes originating from the finishing stage into suitable bags or boxes or other containers corresponding to the different destinations of the envelopes themselves. These destinations can be individual shops if these involve large quantities of processing envelopes, or can be a group of shops where smaller quantities of processing envelopes are concerned.
In either case there is the problem of effecting this sorting in the most reliable, fast and simple manner possible. These requirements can clearly be satisfied to a greater degree the finer the distribution, i.e. the narrower the division of the processing envelopes into their different destinations.
However this requirement, which could be totally satisfied if it were possible to reserve one container for each shop, i.e. for each destination, is however opposed by containing the space requirements of a sorting line within acceptable limits, these requirements being greater the narrower the division into the various destinations. For example, a sorting line for processing envelopes is known comprising essentially an endless mobile chain, to which bottom-openable pockets are applied. Below the path of the pockets there are provided a plurality of bags for collecting the envelopes, to correspond to the different customers or to the particular customer groupings. The processing envelopes originating from the finishing station are inserted automatically into the successive pockets, which then cause them to fall into the bag corresponding to the particular envelope destination, this destination having been previously read from the envelope and used, by means of the reading signal, to cause the various pockets to open when these are positioned exactly above the corresponding bag.
However this known processing envelope sorting line has the drawback of a large plan area and an unsatisfactory limit to the maximum number of bags or boxes which the plant can serve.
A further drawback of this known sorting line consists in that it is scantily flexibile, both for what relates to the utilisation of the space at disposal, and for what relates to its enlargements or modifications due to changed requirements, and in any case such enlargements and modification cause considerable constructional difficulties and high costs.
A further drawback is that the need to group together several destinations during the sorting stage requires a subsequent sorting operation, which is generally effected manually with the aid of a pigeon hole system, and consequently requires further space due to the presence of the pigeon hole system, plus manual operations which slow down and thus increase the cost of the whole sorting operation.